Leucopenia refers to a condition where the absolute count of peripheral blood leucocytes is constantly less than 4.0×109/L. Cytotoxic drugs, toxic chemicals, and ionizing radiation, being the most common causes of decrease in neutrophils, may directly act on the stem cell pool and mitotic pool, impairing, damaging or suppressing hematopoietic stem cells/progenitor cells as well as early dividing cells. Some drugs may interfere with protein synthesis or cell division in a dose-dependant manner, while other drugs have dose-independent actions, possibly induced by allergic or immunological factors. Generally, patients with a slight decrease may mostly show primary symptoms, without clinically specific symptoms. Patients with a moderate or severe decrease are susceptible to infections and non-specific symptoms such as fatigue, weakness, dizziness, loss of appetite, etc. Leucopenia induced by radiotherapy or chemotherapy is the main reason why patients with malignant tumors often fail to complete the therapy. Administration of leukogenic drugs during an early stage of leucocyte decrease after radiotherapy or chemotherapy may substantially increase the number of leucocytes and allow patients to effectively and smoothly complete the chemotherapy and to improve their survival and quality of life, which represents a new approach to prevention and treatment of tumors. Patent Application CN101292742A discloses a pharmaceutical composition comprising Ganoderma, Radix Panacis Quinquefolii and fermented Cordyceps sinensis powder, which functions to enhance immunity. Patent Application CN102228252A discloses a composition of traditional Chinese medicines comprising Radix Panacis Quinquefolii and/or Radix Et Rhizoma Ginseng, Ganoderma, and fermented Cordyceps sinensis powder, which functions to alleviate physical fatigue. Patent Application CN102000129A discloses a pharmaceutical composition comprising Cordyceps polysaccharides or fermented Cordyceps sinensis powder, Ganoderma, and Radix Panacis Quinquefolii, which functions to enhance immunity. Up till now, no report or literature shows that a composition made from Ganoderma, Radix Panacis Quinquefolii or Radix Et Rhizoma Ginseng, fermented Cordyceps sinensis powder and/or Cordyceps has a function of preventing and treating leucopenia induced by radiotherapy or chemotherapy.